1. Field of the Invention
The present invention relates to a liquid-droplet jetting apparatus which jets a liquid droplet from a jetting port.
2. Description of the Related Art
In an ink-jet head (liquid-droplet jetting apparatus) which jets an ink from jetting ports of nozzles by applying pressure to the ink in pressure chambers, when pressure is applied to the ink in a certain pressure chamber among the pressure chambers, pressure wave is generated in the pressure chamber, and the generated pressure wave is propagated to a common liquid chamber communicating with the pressure chambers. This pressure wave is attenuated in the common liquid chamber to prevent the pressure wave from propagating further to another pressure chamber, thereby suppressing the variation in ink-jetting characteristics such as change in droplet speed. For example, an ink-jet type recording head (ink-jet head) described in Japanese Patent Application Laid-open No. 2003-127354, a plurality of pressure generating chambers (pressure chambers) communicating with nozzles respectively are communicated with an ink storage chamber (common liquid chamber) via ink supply channels, respectively; and a recess is formed in a head case at an area corresponding to the ink storage chamber. Further, a metallic vibration plate has an area overlapping with the area of the head case at which the recess is formed, and this area of the vibration plate functions as a damper which releases the pressure variation (damps or attenuates the pressure wave) in the ink storage chamber.
However, with respect to the ink-jet head described in Japanese Patent Application Laid-open No. 2003-127354, when an attempt is made to realize the high densification and miniaturization of the ink-jet head, it is necessary to decrease the size of the common liquid chamber, and if the common liquid chamber is decreased in size, there is a fear that the pressure wave is not sufficiently attenuated in the common liquid chamber. In such a case, it is conceivable to form a member, such as the vibration plate which functions as the damper, of a material with a low elasticity such as polyimide. This, however, in turn causes a problem such that, when this member is heated together with another member made of metal and joined to the another member, warpage deformation occurs due to the difference in linear expansion coefficient between the members.
An ink-jet head described in Japanese Patent Application Laid-open No. 11-309877 is provided with two reservoirs which supply an ink to pressure generating chambers communicating with nozzles, respectively, such that the reservoirs are overlapped in an up and down direction. The two reservoirs are partitioned by a partition plate which is provided with a pressure-absorbing section for absorbing a pressure wave generated when the ink droplets are discharged and directed in a direction opposite to openings of the nozzles. The partition wall is formed by joining a thin plate and a sealing plate which has a recess formed therein, and the pressure wave is absorbed by the thin plate and a thin wall defining the recess.